By using Ab initio approach, we have analysed Silicene-, Germaneneand Graphene-based molecular single-electron transistors. It is based on non-equilibrium greens function (NGEF) and density functional theory (DFT). Three different fullerene molecules are taken and optimization is done. In Coulomb blockade regime, silicene, germanene and graphene are kept above gate dielectric between drain and source for weak coupling. We have taken gold electrodes for SET environment. Gold is widely used as metal electrode in nanoscale devices. We have calculated the HOMO and LUMO values and total energy versus gate voltage. Charge stability diagrams are obtained by calculating charging energy as function of external gate potential. By these calculations, the analysis of three different molecular single-electron transistors is done. The total energies of these molecules are highly negative (very low) compared to other molecules.
We investigate here
the strain-induced growth of Cu at 600 °C
and its interactions with a thermally grown, 270 nm-thick SiO2 layer on the Si(111) substrate. Our results show clear evidence
of triangular voids and formation of triangular islands on the surface
via a void-filling mechanism upon Cu deposition, even on a 270 nm-thick
dielectric. Different coordination states, oxidation numbers, and
chemical compositions of the Cu-grown film are estimated from the
core level X-ray photoelectron spectroscopy (XPS) measurements. We
find evidence of different compound phases including an intermediate
mixed-state of Cu–O–Si at the interface. Emergence of
a mixed Cu–O–Si intermediate state is attributed to
the new chemical states of Cu
x+, O
x
, and Si
x+ observed
in the high-resolution XPS spectra. This intermediate state, which
is supposed to be highly catalytic, is found in the sample with a
concentration as high as ∼41%. Within the Cu–O–Si
phase, the atomic percentages of Cu, O, and Si are ∼1, ∼86,
and ∼13%, respectively. The electrical measurements carried
out on the sample reveal different resistive channels across the film
and an overall n-type semiconducting nature with a sheet resistance
of the order of 106 Ω.
Abstarct. Two dimensional (2D) derivatives of tin (Sn) have obtained special deliberations recently due to practical realization of planar, as well as, buckled hexagonal lattice of Sn called stanene. However, it has been observed that proper choice of substrate is very important for growth of stanene like films owing to large core size of Sn that prefers sp
3 hybridization over sp
2. Transition metal dichalcogenides (TMDs) like MoS2 or WS2 with honey comb lattice structure seem to be promising substrate candidates for 2D growth of Sn. In the present work, we report mechanical exfoliation of few layers of WS2 under ultra-high vacuum (UHV) conditions and investigations of growth and local electronic structure by in-situ scanning tunneling microscopy (STM) and spectroscopy (STS) studies. Flat WS2 surface with honeycomb lattice structure in the atomic scale with a lattice constant of 0.34 nm is evident in the STM investigations, whereas, STS measurements reveal local density of states (LDOS) of WS2 with a bandgap of approximately 1.34 eV. Density functional theory (DFT) calculations performed by considering bulk WS2 reveal conduction and valence band states comprised of S p and W d at both sides of the Fermi energy (EF) and an indirect bandgap of 1.38 eV. Experimental observations upon Sn adsorption, reveal commensurate growth of Sn atoms on the sulfur `S’ sites with a buckling height of 40 ±10 pm. STS measurements exhibit local electronic structure of the Sn adsorbed surface with clear evidence of in-gap states. DFT calculations quantify the experimental results demonstrating `S’ sites as the most stable sites for the atomic adsorption of Sn with a buckling height of around 80 pm and reveal signature of in-gap hybridized states comprised of Sn p and W d orbitals.
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